The invention relates to the field of interferometric-spatial-phase imaging (ISPI), and in particular to nanometer-precision referencing of a scanning probe tip to a substrate.
Since the invention of the scanning probe microscope in 1981, tip position has been subject to drift and perturbations that introduce disparities between the tip position and its intended position on a Cartesian grid. Tip perturbations degrade the quality of scanned images. Of more significance is the application to scanning probe lithography, which has been shown to write sub-5 nm features, and manipulate single molecules. Precise tip control, a priori, and contemporaneous to lithographic patterning, is essential for viable lithography at the extreme limit of molecular patterning.